This invention relates to pressure release vents for electrolytic devices.

An object of the invention is to improve pressure release vents for electrolytic devices such as electric current producing cells, dry batteries and cells, electrolytic condensers and the like.

Another object is to improve the protective means against liquid leakage in vented `cells and devices. l

`Other objects of the invention will be apparent from the description and claims.

Figure 1 is a side view, partly in section of a primary cell embodying features of the invention;

Figure 2 is a bottom view thereof;

Figure 3 is a side view, partly in section of a modifi-ed cell construction;

Figure 4 is a partly sectional view of a cell having a pressure release vent together with an enclosing casing containing a liquid absorbent or neutralizer; and

Figures 5 and 6 show further variations of cells having liquid absorbent in outer casings. One feature of the invention resides in an emergency vent arrangement for electrolytic cells and devices comprising a grooved wall member enclosing the cell elements. The member is adapted to split or spread to afford a iiuid release should pressure develop. vIn its preferred form the weakening comprises crossed grooves or cuts in a metal wall which do not penetrate through the wall. Another feature resides in the combination of an emergency vent with an external receptacle for receiving any liquid which may issue from the vent. An absorbent or neutralizing material may be included in the receptacle.

Certain electrolytic devices, such as primary cells and electrolytic condensers, are substantially free from gas generation during normal use but sometimes are subject to gassing under unusual conditions, such as improper use, undue heating or the presence of excessive impurities; One type of primary cell develops very little or no gas during use but in some cases will produce a quantity of gas after the end of its useful electrical life.

It is desirable that such cells and condensers be completely enclosedand sealed to prevent leakage or evaporation vof electrolyte and reaction of the cell elements and electrolyte with air. The vent arrangements described herein provide a complete seal under normal conditions but permit convenient release of pressure if it should develop during use or at the end of the cell life.

.2 The present application is related to a copending application of Fred D. Williams, Jr., Serial No. 679,117, filed June 25, 1946, now Patent No. 2,478,798, dated August 9, 1949,' for Primary Cell. In the said co-pending application, there is disclosed and claimed an electric current producing cell comprising a sealed container having cell elements and an electrolyte therein, a metal wall of said cell having a slit extending therethrough and normally closed by the metal-to-metal contact of the surfaces de'- iining said slit, said slit being capable of opening responsive to excessive internal pressure.

Referring to the drawings, Figures 1 and 2 illustrate a primary cell comprising a steel can or container I0. The cell is sealed with a top disc II and sealing ring or grommet I2 of insulating material.- 'Ihe cell contains the usual cell elements which may, for example, comprise an electrode I3 secured to top disc II, spacing material I4 containing an electrolyte, and an electrode I5 pressed into the bottom of the container.

According to the invention the plane bottom wall I6 of the container III has cut or impressed therein a pair of crossed chisel grooves I1 and IB. Preferably these extend for about one-third the diameter of the can and penetrate to a depth of about 75 to 85% of the wall thickness. The

grooves cross each other at an angle which is desirably about The grooves can be cut with a chisel or' sharp edged tool by placing the empty container over a m'etal pedestal, placing the tool in the desired position and, striking it with a hammer. can also be made on a metal stamping press provided with a suitable tool.

Since grooves I1 and I8 do not penetrate through the bottom I 6 the cell remains sealed under normal conditions. However, should gas pressure develop within the cell suiilcient to bulge out bottom wall IB slightly, the tension produced by the bulging will start a split or tear in the metal of wall I6 at the crossed grooves. This will open up a minute split or crossed splits. Ordinarily this will be sumcient to allow escape of the gas and the bulging will disappear so that the splits close tightly together. Additional gas generated can still escape but the cell is still substantially closed.

In one type of primary cells the generation of gas ordinarily takes place only at the end of the cell life at which time pressed electrode I5 will havebeen consumed or decomposed so that ready access of the gas to the vent is possible. In instances where gas pressure builds up be- They :are electrode s has l 3.; v been consumed anni.

Figure 3 shows the invention applied to a different cell construction'. The cell container 30 has its bottom 36 grooved internally4 at 3,1 with v a pair of crossed grooves. The cell electrodes, and 35 and spacer 34 rest on a disc 38 o1 sheet insulation which covers the groove. The operation when gas pressure develops is similar.

spaced slightly from bottom I6 of the cell. The tube and bottom may -be of waxed-cardboard,

vpaper or of metal or partly cardboard and partly our or diatomaceous earth.

- 4Figure 5 illustrates an outer tube construction adapted to provide a bottom terminal for the cell i0. Thiscomprises a cardboard cylinder 50 rolled over the rim of a sheet metal bottom I of steel, tinned steel, copper or other metal. A

Vv'or a mixture with an absorbent suchv as wood metal tab strip 52 is welded or soldered at 53 to l the wall of cell l0 and at 54 to the inside of metal bottom disc 5|. The space between disc 5i and the bottom of cell I0 contains composition 42.

Figure 6 shows a further modication in which the material 42 is contained in a shallow metal cup 6l which is welded or soldered at two or three points 62 to the bottom of cell Il). A cardboard tube 60 encloses the side wall of the cell, if desired. There is suillcient leakage between the rim of cup 6l and bottom of cell I0 at the unwelded points to allow escape'of gas, on venting.4

It'will be seen 'that the present invention provides for an emergency cell vent'which becomes.

elective only if excessive gas pressure should develop within the cell. Itis economical, of material, labor and space.

Itisobvious that certain variations can be made in. thelocationand shape of.- the vent grooves and in vother. features of construction without depart-l ing from the luy/entren... V Y While;I specic embodiments. op the.: ,invention` .prisel- 14. "me een as describes inf-claims 3L :The .een as abi-scribed ized in emctnehousiag' 6. The cell as ized in that the housing'fisfxfs'urrounded byjnex-V 'ternal receptacle centainlggan'fabsorbent. in edium ' Y 7. 4'Elihe cell as described 2eharacter'd ized in that the housing is surrounlziedv by -a metal receptacle containing a neutralizar for .the

rigid metalv housing containing at least one of said electrode elements and constituting part of the cell enclosure, and an elongated narrow groove formed in a wall of said housing and providing an integral linear wall portion of reduced thickness, said wall portion of reduced .thickness constituting a positively ydetermined tear line along which said housing will split in response to excessive internal gas pressure.

- 9. An' enclosed dry cell comprising in combina-v v tion positive and negative electrodes, an electrolyte for said electrodes, a rigid metal housing containing at least one of said electrodes constituting part of th cell enclosure and one of the terminals of the cell, and an elongated narrow groove formed in a wall of said housing and providing an integral linear wall portion of reduced thickness, said wall portion of reduced thickness constituting a positively determined tear'line along which .said housing will split in response to excessive internal gas pressure.

10. In combination with an enclosed dry cell comprising a pair of metal housing members, an

' insulative member confined between cooperating have been described;itp-isl intended't'o. covers-the.: -Y

invention broadly 'within the spiritvandfscopef of' V-shaped grooves in a centralarea thereof, said: l grooves extending for about l@ the said end wall and lpenetrating from 75% tov 90% l of said wall thickness.

Aa rigid metal wall in electrical connection with one of said 'electrode elements and constituting part of the cell enclosure, and an elongated narrow groove formed in said wall providing an integral linear wall portion. of reduced thickness, said wall portion of reduced thickness constituting a positively determined tear line along whichv said wall will split in Vresponse to excessive internal gas pressure.

cell comprisportions of said housing members and constituting therewith an enclosure for the cell, a pair of electrodeelements within said enclosure and in respective electrical contact with said housing members, an electrolyte for said electrode elements, and' emergency venting means for said lcellresponsive to excessive internal gas'pressure developed within saidenclosure; an outer con-i' tainer partiallyenclosingsaidcell and-jdening 1 therewith a space. into whicl1 .s`aid venting. means t openstpleastiamrtion--of said' .outer ,containerl being.,formedjrofmetals"andganfelectricaliconnece'f*- tionfbetween one. of saidhousing y'members' and.; the metal portion of saidoutr'container whereby said metalportionv will'constitute-*one' of the external terminals of the cell. y FRED'D. WILLIAMSJR. 1